 .customTab{
     ul {  
        width: 100%;
        height: 0.8rem;  
        position: relative;
        border-bottom: 1px solid #ccc;
        li { 
            float: left; 
            width: 25%;  
            height: 0.8rem;  
            text-align: center;  
            span {  
                font-size: 0.25rem;
                color: #848789;  
                text-decoration: none;  
                line-height: 0.8rem;  
            }  
        } 
        li:last-child{  
            width: 20%;
            margin: 0 2.5%;  
            border-top: 0.03rem solid red;/*只需要将上边显示出来*/  
            position: absolute;  
            top: 0.76rem;  
            transition: left .2s ease-in-out 0s;/*包含四个过度属性：执行变换属性、执行时间、速率、延迟*/  
            -webkit-transition: left .2s ease-in-out 0s;/*chrome和safari*/  
            -moz-transition: left .2s ease-in-out 0s;/*firefox*/  
            -o-transition: left .2s ease-in-out 0s;/*opera*/  
        }   
    }
 }
